多中段联合开采围岩扰动效应及采矿进路支护技术

Surrounding rock disturbance effect of multi-middle section combined mining in stopes and support technology of mining roadway

受多次开采扰动影响,多中段联合开采过程中采场围岩稳定性差,地压显现剧烈,采矿进路支护难。以白象山铁矿-470,-430和-390 m中段联合开采工程为研究背景,采用大型相似材料模型试验及采场围岩数字照相变形量测技术,揭示多中段联合开采采场围岩应力变化特征及上覆岩层移动规律。研究结果表明:各中段逐分层向上回采对上覆岩层产生了累积叠加扰动效应,导致采场围岩反复承受荷载(多次扰动)而失稳破坏;各分层矿体下沉量随开采步的推进呈先增大后减小的趋势,采空充填区中部位置附近覆岩的下沉量最大,采场围岩变形具有明显的阶段性增长特征。各中段保留矿体(顶柱)对维持采场围岩稳定、减弱相邻中段间的采矿扰动和降低上覆岩层的变形破坏有积极的作用,受多中段联合开采扰动影响较大、完整性破坏严重的中段保留矿体中的应力可突然释放,出现了局部或整体失稳,威胁采场围岩整体稳定性。确定多中段联合开采扰动条件下采矿进路切圆拱断面形式,其拱高为2.0 m,提出锚网索喷联合支护技术,有效控制采矿进路围岩变形与破坏。

Under the action of multiple mining disturbances,stability of stope surrounding rock is deteriorated,ground pressure presents appears,and mining roadway support is difficult in the process of multi-level joint mining.Taking multi-level joint mining engineering of−470,−430 and−390 m in Baixiangshan Iron Mine as research background,large-scale similar material model test and digital camera deformation measurement technology of stope surrounding rock were used to reveal stress variation characteristics of stope surrounding rock and movement law of overlying strata in multi-level joint mining.The results show that stratification-by-layer upward mining in each middle section produces a cumulative superimposed disturbance effect on the overlying strata,resulting in the instability and failure of stope surrounding rock under repeated load(multiple disturbances).Subsidence of each layered ore body increases firstly and then decreases with the advance of the mining step.Subsidence of rock near middle position of goaf filling area is the largest,and deformation of stope surrounding rock has obvious stage growth characteristics.Reserved orebody in each middle section has a positive effect on maintaining stability of stope surrounding rock,weakening mining disturbance between adjacent middle sections and reducing deformation and failure of overlying strata.Stress in the reserved ore body having serious integrity damage in the middle section at the disturbance of multi-level joint mining can be suddenly released.Local or overall instability poses a threat to the overall stability of stope surrounding rock.Section form and arch height with 2.0 m of tangential arch of mining roadway under the disturbance condition of multi-level joint mining are determined,and bolt-mesh-cable-shotcrete combined support technology is proposed,which effectively controls deformation and failure of mining roadway surrounding rock.